Mediterranean diet and cognitive decline over time in an elderly Mediterranean population

Evidence suggests that dietary patterns compatible with the traditional Mediterranean diet (MD) may protect against cognitive decline. We prospectively assessed whether adherence to MD in the Mediterranean country of Greece is inversely associated with cognitive decline in the elderly and whether any particular MD component may play a key role.

Elderly men and women (N = 401) residing in the greater Athens area had dietary variables ascertained in 1994-1999. Adherence to MD was represented by the MD score [MDS, 0-3 (low), 4-5 (intermediate), 6-9 (high)]. The mini-mental state examination (MMSE) was administered by trained professionals to individuals aged 65 years or older in 2004-2006 (first assessment) and re-administered in 2011-2012 (second assessment). MMSE change (cMMSE) was categorized as: improved/unchanged (cMMSE ≥ 0), mildly lower (cMMSE -1 to -4) or substantially lower (cMMSE ≤ -5). Associations were evaluated through multinomial logistic regression.

Decline in MMSE performance was inversely associated with adherence to MD. For mild versus no decline, odds ratio (OR) comparing high to low MD adherence was 0.46 [95% confidence interval (CI) 0.25-0.87, p = 0.012]. For substantial versus no decline, OR comparing high to low MD adherence was 0.34 (95% CI 0.13-0.89, p = 0.025). Among the nine MDS components, only vegetable consumption exhibited a significant inverse association with cognitive decline.

Closer adherence to the traditional MD is highly likely to protect against cognitive decline in this elderly Mediterranean population. Higher vegetable consumption appears to play a key role, possibly in synergy with additional components of the diet.